Components made of composite materials play an increasing role in everyday life and are increasingly used for structural components, where the possibility of obtaining parts with high stiffness and strength properties yet low weight are important or advantageous. Thus, composite structures are used more and more in the manufacture of parts and finished goods in various industries such as in the wind turbine, automotive, trucking, aerospace, marine, rail, appliance, container, construction, anti-corrosion, electrical and medical industries as well as in athletic equipments, recreation vehicles and such.
For most components, the properties of the surfaces play an important role such as for instance high resistance to UV-light, hardness, low friction coefficients in specific areas, surfaces that are easy to repair without visual impair, and low or high reflection coefficients etc. depending on the specific requirements and use of the component in question.
Hydrophobic properties are very advantageous especially in many outdoor applications in yielding a self-cleaning and dirt-repelling effect as small particles, contaminants and insects etc are more easily washed off with the water being repelled from the hydrophobic surface due to its low surface energy. A similar self-cleaning effect is obtained on surfaces with the so-called lotus effect characterized by small elevations and depressions, or a very porous surface structure in the micro- and/or nano-scale containing trapped air. Such surfaces are also advantageous in reducing the noise, e.g. arising from the blades on a wind turbine, in use and in reducing the drag from a surrounding fluid. Such surfaces and methods for their manufacture are described in EP1141543, EP0772514, DE102004037812 and U.S. Pat. No. 7,258,731 among others. A significant disadvantage with the described self-cleaning surfaces is, however, that the self-cleaning and dirt-repelling effect is prone to be worn off after a relatively short period of time of course depending on how the component in consideration is used. The surface properties will then have to be renewed for instance by spraying, painting or in another way applying a new coating. This is in many applications a very impractical or perhaps even impossible procedure to perform and is in all cases both very time-consuming and costly.
EP1283076 describes a method of obtaining a hydrophobic surface structure which is at least partly self-regenerating. The surface is formed by securing particles on and in a carrier layer. When the carrier layer and the particles on the surface along with it are worn off, new particles are gradually exposed regenerating the surface properties. The coating is applied by spray, brush, a jet or the like which, however, is disadvantageous for a number of applications as only a relatively thin layer thickness can be obtained by these methods as the layer otherwise has a tendency to become wrinkled and uneven and the strength of the layer will be limited. Alternatively, in order to obtain a thicker surface layer of a higher strength, the coating must be applied by a number of thin layer applications which then render the manufacturing method time-consuming and uneconomical.